Reduced selection leads to accelerated gene loss in Shigella.
Reduced selection leads to accelerated gene loss in Shigella.
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DOI：
10.1186/gb-2007-8-8-r164
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发表时间：
2007
期刊：
影响因子：
12.3
通讯作者：
Petrov DA
中科院分区：
文献类型：
--
作者：
Hershberg R;Tang H;Petrov DA
研究了兼性致病菌E.大肠杆菌和志贺氏菌，并发现更大的利基限制志贺氏菌。这被证明是由于选择的有效性在全基因组范围内降低。专性致病菌相对于兼性病原体丢失更多的基因，而兼性病原体又比自由生活的细菌丢失更多的基因。有人认为，专性病原体中基因丢失的增加可能是由于纯化选择的有效性降低。很少有人注意到兼性病原体中基因丢失增加的原因。我们详细研究了两组兼性致病菌的基因丢失率：致病性大肠杆菌和志贺氏菌。我们发现志贺菌菌株相对于致病性大肠杆菌以更快的速度丢失基因。杆菌我们证明，全基因组范围内减少选择的有效性有助于观察到的志贺氏菌基因丢失率的增加。与近缘致病性E.大肠杆菌的亲戚，更小生境限制志贺氏菌菌株似乎正在失去基因在一个显着加速。全基因组范围内净化选择的有效性降低在产生这种观察到的差异方面发挥了作用。我们的研究结果表明，选择的有效性的差异有助于在兼性致病菌的基因丢失率的差异。我们讨论了志贺氏菌的生活方式和致病性如何可能改变选择的有效性，从而影响基因丢失率。
The rate of gene loss was studied in the facultative pathogens, E. coli and Shigella, and was found to be greater in the more niche-limited Shigella. This is demonstrated to be due to a genome-wide reduction in the effectiveness of selection. Obligate pathogenic bacteria lose more genes relative to facultative pathogens, which, in turn, lose more genes than free-living bacteria. It was suggested that the increased gene loss in obligate pathogens may be due to a reduction in the effectiveness of purifying selection. Less attention has been given to the causes of increased gene loss in facultative pathogens. We examined in detail the rate of gene loss in two groups of facultative pathogenic bacteria: pathogenic Escherichia coli, and Shigella. We show that Shigella strains are losing genes at an accelerated rate relative to pathogenic E. coli. We demonstrate that a genome-wide reduction in the effectiveness of selection contributes to the observed increase in the rate of gene loss in Shigella. When compared with their closely related pathogenic E. coli relatives, the more niche-limited Shigella strains appear to be losing genes at a significantly accelerated rate. A genome-wide reduction in the effectiveness of purifying selection plays a role in creating this observed difference. Our results demonstrate that differences in the effectiveness of selection contribute to differences in rate of gene loss in facultative pathogenic bacteria. We discuss how the lifestyle and pathogenicity of Shigella may alter the effectiveness of selection, thus influencing the rate of gene loss.